


you are coming down with me, hand in unloveable hand

by cashtastrophe



Series: goddamn, we missed the vein [5]
Category: Underfell - Fandom, Undertale (Video Game)
Genre: Abuse, Alternate Universe - Underfell, Bloodplay, Breathplay, Drugs, F/M, Jealous Papyrus, Kinda, M/M, Masochism, Piercings, Possessive Behavior, Sins, Tongue Piercings, Torture, Underfell Papyrus, Underfell Sans, Underfell Undyne, Waterboarding, Yandere Papyrus, and making everyone uncomfortable, blowjob, papyrus is super gross, undyne is an angler fish, undyne is exploring her sexuality
Language: English
Status: Completed
Published: 2016-09-01
Updated: 2016-09-03
Packaged: 2018-08-12 11:19:53
Rating: Explicit
Warnings: Graphic Depictions Of Violence, Rape/Non-Con, Underage
Chapters: 2
Words: 7,591
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/7932700
Author URL: https://archiveofourown.org/users/cashtastrophe/pseuds/cashtastrophe
Summary: <blockquote class="userstuff">
              <p>“I need you to summon your tongue again,” Papyrus says, softly. “And if you dispel it before I expressly tell you to, I'm gonna <i>take your fucking legs off</i>. You hear me, runt?”</p><p>(in which undyne learns some stuff she doesn't want to learn and papyrus handles things badly.)</p>
            </blockquote>





	1. i hope you die

**Author's Note:**

> soooooo y'all can blame this on mistressminako who gave me a drabble prompt. 3,000 words later, here we are. 
> 
> this is the first chapter of a short little thing i've been wanting to write for a while, probably just two parts. second part's gonna be real gross. get stoked.
> 
> also, melusine is undyne's mother, who has been mentioned before in this verse, but not by name.

The absolutely most unsettling thing about sans, somehow, has nothing to do with the fact that he's a walking, talking horror movie cliche. It has nothing to do with the way his eye sockets go dark and flat sometimes, this endless pit of absence so black Undyne can't really tell if she's staring into negative space or not. It looks tangible, almost, like if she put her fingers to it there might be a texture pressing back.  
  
(She thinks it would be something soft and strange, the thick velvet plush of moss on stone coupled with the familiar sticky heat he usually exudes. It's always a disarming reminder that he is a living creature still.)  
  
He doesn't look at her as she drops onto the bench next to him, but that's nothing new. He stiffens a little, the same instinctual twitch he's had the whole time she's known him, so she knows he's aware of her at the very least. She's never sure if they can actually _see_ , when their eyelights vanish like that and it always seemed like a bad time to ask, somehow.  
  
Undyne is still dripping wet, staining the unfinished wood a darker shade where her slick skin touches it. It's not like she had anywhere to stash a towel, though, when she'd started her swim. Besides, her scales dry quickly enough, even if her suit is already starting to feel kind of clammy and uncomfortable against her belly. sans doesn't seem particularly bothered by it.  
  
He's barefoot, which she knows usually means that he'd left the house in a hurry. She can see from here, in the v of his hoodie collar, that he doesn't have a shirt on. There's a thick, bright band of bruising around his throat, not quite hidden by his tattered collar. Two fingers on his left hand are bandaged together poorly, using what looks like a piece of scrap metal as a makeshift splint. A brand-new crack in his brow bone bleeds sluggishly, dark red smear on grey bone where he'd scrubbed a hand over his face.  
  
Those are _all_ new, she notes absently. She's known him long enough, she's familiar with his usual catalogue of injuries to be able to roughly date them by this point. It's this morbid little game of pseudo-forensics she plays with herself every time she sees him. She's not enough of an asshole to point it out aloud—she had, once, when she was much younger and entirely tactless, poked a large bruise wrapped around his right wrist and demanded “Hey, where did you get _that_?” He hadn't answered, but he had cringed away like she'd slapped him.  
  
Undyne _really_ hadn't liked what that did to her stomach, this awful plummeting feeling, like the way she jolted awake sometimes with her heart slamming against the inside of her chest. Watching Sans cower away from her felt like being jerked suddenlyfrom some vague, terrifying nightmare certainty that something was coming for her.  
  
She didn't mention it again.  
  
On some level maybe she just....thinks there should be someone to notice. He doesn't even try to hide them, really, doesn't bother wearing that thick jacket at all when he's indoors. Somehow, that's worse than if he'd been perpetually hidden in long sleeves. She has a hard time avoiding the lurid blooms of reds and purples on his bare bones this way, has a hard time not looking at Papyrus and thinking _why don't you stop him?_  
  
It's none of her business.  
  
(Once, though, for a horrifying full week, he's just....missing his entire right arm from the shoulder down.  
  
It leaves him pale and sweating and shaking with pain. Leaves him shivering like he's got a fever, barely coherent enough to manage full sentences...but no one says a word, and what is _she_ supposed to do about it, exactly? She doesn't even want to be involved but here she is anyways. Always had been—or as involved as anyone outside that fucked-up little family unit can possibly be, she guesses.)  
  
Papyrus makes her complicit. It's hard not to resent him for it, only a little, even though she sees the way his finger bones ball into white-knuckled fists every time the doctor spits sans's name like a four-letter word.  
  
Melusine—not _Momma_ anymore, not now that she's seventeen and practically grown, Undyne reminds herself firmly—doesn't think much of the doctor to begin with. Never has, she told Undyne the very first time she saw sans cringing in Gaster's shadow as they waited outside the school for Papyrus. She didn't like him when he was courting Papyrus's mom and she certainly didn't like him any better once he'd fathered her little brat.  
  
“He was so arrogant,” Melusine said that night, carding her claws through Undyne's unruly mane, soothing out the knots with gentle strokes. “Didn't think much of us, that was clear. 'Dumb muscle,' I think I heard him call us, once. Not to Lexi, of course, but still. No respect for anything but his stupid little calculations.”  
  
She made a face over Undyne's shoulder in the mirror and it pulled the white scar across her lip in a weird little twitchy half-smile. Undyne giggled. “Lexi would have been great with Papyrus,” Melusine continued softly, combing Undyne's hair into three separate sections for her to plait. She flattened the delicate stalk of the illicium into the center strand carefully. The glow of Undyne's esca flashed as it passed over her head, bright as a shooting star. “He's just like her. Loud as all hell, stubborn as a rock. She'd have been good for him, poor kid.” She paused, seemed to consider and finally said, “And...maybe she'd have been good for the other one, too.”  
  
Undyne sighed and pressed back into the comforting familiarity of her mother braiding her hair, a warm, muscled bulk at her skinny back. “He wouldn't be around if she was,“ she mumbled. “Pap's dad, like... _made_ him to take care of Pap when he was a kid. Frankenstein-style.”  
  
“Oh, well, of course he did. That's turned out well,” Melusine growled. “ _Jesus_. Is that why he's...?” She pinches all three strands in one hand and gestures to her own eye socket with the other, brow wrinkled in disgust. “He's some kind of what, experiment?”  
  
Undyne didn't know how to explain it, so she'd just shrugged. Melusine hadn't pried further. _It's none of their business._  
  
Now, watching him shrink away from her as she rests one arm across the back of the bench, she realizes she still doesn't quite have words for what's _wrong_ about the way he acts. He's smaller than her, weaker, but she's never so much as playfully threatened him in her life. He has no reason to be frightened of her.  
  
The most unsettling thing about sans is that while he clearly doesn't trust anyone, he doesn't lie. Ever. About _anything_. More than that—he answers any questions directed at him like he's under interrogation, delivers them flat and rapid-fire, mostly in the direction of his own feet.  
  
This, she suspects, is a side effect of living with the doctor, because Papyrus is similarly brutal in his honesty. It's as though the two of them can't quite bring themselves to report false data, though unlike his brother, Papyus at least seems to have some sense of appropriate timing, some concept of when to keep his mouth closed. She regrets her question the second it's out of her mouth. sans has no such filters. “sans...what _happened_?”  
  
He laughs, this low husk of a sound that's hollow as his eye sockets, and takes a big, shuddering breath. There is no evidence of tears on his dry cheekbones, though his voice is wrecked, rough like he's been crying. Panic attack, maybe, she thinks.  
  
“Papyrus pulled 'em off,” he offers, wiggling the bandaged digits in her direction just a bit. “and doc slammed my head into the counter cause i was makin' too much noise about it, i guess.”  
  
He shrugs. He slurs his words a little, but he delivers it with all the enthusiasm of reading off a particularly tedious recipe, as though he is boring himself with the report. His uninjured hand reaches up to wipe away the thin trickle of blood making its way down to his nasal cavity and he laughs again. “do me a favor? don't mention that you saw me. i'm supposed to be in the shed.”  
  
Undyne nods, dazed. “Course. I, uh...you want some help with that? I'm not, you know, I'm not _great_ at healing yet but I've got some basic field medicine spells down—”  
  
“naaaah,” he interrupts with a wave of his good hand. “they know i can't do it myself. if i show up all better tomorrow...”  
  
“...they'll know someone helped you. Right.” Undyne huffs out a frustrated breath, her bangs puffing upwards for a moment. “Lucky it's a warm night out.”  
  
“yeah,” he agrees and tips his head back to look up at the false stars studding the ceiling, his sockets half-lidded and heavy. He looks exhausted. A little buzzed, maybe. “what're you doing all the way out here?”  
  
She makes a face. “Mom— _Captain M_ _elusine_ has me training to apply for the academy next season. Hasn't Pap been preparing for it? I see him in the gym every day.”  
  
Sans lifts one shoulder lazily, lets it drop. “dunno,” he deadpans at the 'sky.' “we don't talk much anymore.” His tongue, glowing the same dull, sickly pink as his absent eyesights, flicks out absently from between his teeth to lick the blood from his finger bones. Undyne watches it, fascinated and a little disgusted. He doesn't seem bothered by the taste at _all._  
  
With his neck craned like that, in the dim light of the echo flower nestled beside them, she can see a ring of old, yellowed bruising stamped right into the vertebrae where she guesses his throat might be. She knows from all of Melusine's countless crime dramas that teeth are wholly unique, a bite distinct and individual—not _quite_ as good as a fingerprint, but close.  
  
She wonders if the mark would match Papyrus's broad fangs if she compared the two.  
  
She'd bet on it. They don't have fingerprints, anyways.  
  
“Why'd he...?”  
  
“because he had a shitty upbringing,” sans says evenly, though his voice is tight. “speaking of, i need a favor from you.”  
  
_That_ actually throws her. She's not sure she's ever heard him ask directly for anything before, and certainly never asked anything of _her_. Curious, she cocks her head at him.  
  
He apparently takes this as permission to continue. “i need you to get me something stronger. a—a sedative or whatever, i don't know.” He tilts his face towards hers, just a little. “something that won't, y'know, knock someone out completely? but they wouldn't, like, _feel_ whatever's going on.”  
  
A frozen weight sinks into her stomach like an anchor dropped in a still pond. She gapes at him for a moment, speechless at the sheer _nerve_ of him.  
  
“What the fuck,” she snaps, twisting to face him. “The fuck kinda business you think i'm running? I sell weed, I don't deal in _sedatives_ , you goddamn creep. “ And what, she doesn't ask, would make him come to _her_ of all people for help drugging his brother? She's the closest thing Papyrus has to a friend—she can't imagine he hasn't noticed. “How stupid can you _be?”_ she hisses. “You don't think I'd tell him?”  
  
He blinks at her, eyesights flickering to wavering, confused life. “what?”  
  
“I'm not going to help you hurt Papyrus!” she snarls, throwing both hands into the air in exasperation. “Are you _kidding me?_ He'd break my neck. He'd break _your_ neck. You leave me out of whatever weird shit you guys have going on, I don't—”  
  
“oh. oh—no, it's for me. the drugs are for _me,”_ he clarifies with a little chuckle. “i wouldn't...come on, you...you saw how he gets.”  
  
For the first time in god knew _how_ long, he met her eyes and held, steady. “you know what he's like,” he mumbles, his smile drooping a little, cheekbones flushing a ruddy, humiliated crimson. And then, horribly, “ _please,_ Undyne.”  
  
She caves, of course. What choice does she have?  
  
  
  
*  
  
  
  
  
Thing is, she's not lying to him.  
  
She genuinely doesn't run that kind of business, but she _does_ know those kinds of monsters.  
  
It's not hard, finding him a steady supply of the little white tabs. Doesn't take her more than a few days and she's including a second little baggie with his weekly pickup. Those times when the shadows dragged beneath his eye sockets start to blur into the bruises, she wheedles a handful of blue pills out of her contact too...though sans never seems to know _quite_ what to do with that generosity and tries to hand them back every time.  
  
They...help, she supposes. He looks better, anyways, his smile blurry and uncertain, rather than pulled painful and tight. She tells herself it's an improvement, the way he stumbles and nearly loses his footing, sometimes, instead of the constant trembling. She tells herself she's helping him when she watched him knock a cracked radius hard against a doorway and fail entirely to notice.  
  
“I can't wake him _up_ ,” Papyrus complains sometimes, and she always smiles to herself when he does.  
  
She and sans don't talk, really, during the pickups. She doesn't ask how he is and he doesn't thank her, so it's not...he was already buying from her, sort of. They're not having any kind of deep conversations. She doesn't even smoke him out the way she does some of her clients. She's not entirely sure why this feels different.  
  
And then once, not seven months into this arrangement—somehow, she finds herself looking forward to their meeting each week, bizarrely, looking forward to the warm clasp of his fingers around hers which doesn't make the slightest bit of _sense_ —that her contact finally runs dry.  
  
“Just for a few days,” he assures her over the phone. “Look, I'll bring it over to you myself the second I get a drop-off, okay? Shit happens, Undyne. I'm a drug dealer, not a pharmacist, and I'd appreciate it if you got off my _dick_.”  
  
He hangs up, conveniently missing the create litany of curses she snarls into the receiver, largely centering around the inadequacy of the aforementioned organ. More's the pity.  
  
This, she thinks later that afternoon, as she stands knee-deep in snow behind the doctor's house in the biting cold and stares down sans's single burning eyelight, is _exactly_ why she doesn't deal in the hard stuff.  
  
No one ever got hooked on weed. No one ever did more than complain at her or demand refunds when _her_ supply ran dry, but there is a definite familiar tension to his shoulders that she doesn't care for at all. His claws click against one another absently. He always looks like he's baring his teeth, but now they're parted, like he's panting a little, the faint glow of his tongue seeping between their uneven edges. She can hear a tiny metallic noise as he drags his tongue piercing along the edge of his gold tooth, a habit she'd always found kind of gross.  
  
“What do you _mean_ , 'you're out?'” he says and it crackles like heat lightning in his throat. Undyne swallows, very much in spite of herself.  
  
“He said it'll be a few days before he can get more. It happens, sans. I don't know what to tell you.” She spreads her hands in exasperation. “Look, it's not like you _pay_ me for this shit, I don't know what you're complaining about.”  
  
“i'll pay you,” he says immediately, sockets enormous, too wide and desperate in his busted face, fixed eerily on her. “is that the issue? Undyne, i'll give you whatever you want, i'll—” he shivers. “i'll do anything, _please_.”  
  
And the thing is...Undyne, she doesn't think about things, sometimes. Often. Well, frequently enough for it to be kind of an issue for her, anyways, the way she moves with her animal impulse quite before her higher brain has processed what she intends to _do_.  
  
It makes her a genius in battle, maybe, because she moves sometimes before her opponent has even made conscious decision to strike, but it's not a good strategy for, say...dealing with your best friend's severely unstable brother, shaking minutely in the beginning stages of withdrawal. Her animal instincts don't know what to do with the terrified, trembling slump of his shoulders any more than she knows what to do with Alphys's miserable hunch when she shows up to school with new marks blooming all down her yellow arms. She knows only that she's bigger than him, and stronger and that means she has _some_ kind of inherent responsibility for his well-being, but she'd also once watched him nearly murder a girl for daring to touch his brother and—  
  
—she's kissing him before she really clocks that she's even leaning towards him.  
  
It's weird. It's uncomfortable. She regrets it the moment they touch because flesh and exposed bone do _not_ work well together. She also doesn't really have a reason for it that she can name, except that one time he'd given her a purple band-aid and told her a shitty joke when she'd skinned her elbow. Except he cringes when anyone says his name. Except his voice shakes just like Alphys's, sometimes and he loves his brother like he loves those goddamn pills. Maybe more. If it was gonna be any guy, this stupid little thing inside her says, it would have been him.  
  
He _lets_ her just manhandle him, though, which is the very worst part. He doesn't jerk away, he doesn't yell at her, he doesn't stumble back, he just...kind of stills under the big hands wrapping around his humeri. He goes slack in her grip and lets his teeth part to make way for her tongue. His whole body arcs into hers like a comma, his slight weight pressing into her almost as though it's reflex.  
  
It probably is.  
  
“Well,” she says, way too brightly, and lets go of him. She drops him back down to his feet and pats him on the shoulders hard, like she's clapping away dust. Grins so wide it hurts. “Answers _that_ question, I guess. Turns out I'm gay as hell, man. Sorry.”  
  
He laughs, obligingly, a little unsteadily. “what, _that_ was the litmus test?” His voice is low, calm, but his eyelights are shrunk to horrified little pinpricks, fixed somewhere a good distance above her head.  
  
Right where Papyrus's window would have been, she realized much too late. By the time she twisted around to look up at him, Papyrus had already pointedly turned away from them, though the arms folded tightly over his chest don't leave much doubt as to whether he'd seen or not.  
  
She never wanted to be involved, and yet.  
  
Here she fuckin' was _anyways_.  
  
  
  
  
  



	2. i hope we both die

**Summary for the Chapter:**

> i should be asleep
> 
>  
> 
> instead, this. i'm sorry. 
> 
> please heed the tags.

  
  
Papyrus doesn't bring it up for _weeks_. sans, as always, waits for the other shoe to drop.  
  
And waits.  
  
And waits.  
  
And _waits_.  
  
  
  
  
*  
  
  
  
The thing is, he was never _actually_ afraid Papyrus was going to kill him.  
  
“I wouldn't,” he'd slurred into sans's collarbone once, half-collapsed into his chest. Papyrus had been fourteen at the time, wasted and subsequently even more awkward in his half-grown body, nearly impossibly to maneuver from sans's own shorter height. It had been nothing but dumb luck that Papyrus had managed to stay on his feet until they reached his bed in the first place, not to mention the fact that he had tipped forwards onto his comforter, instead of back into sans's probably-useless arms.  
  
It was the first time sans had been the one to find the kid post-liquor cabinet raid, though the fact that Papyrus had polished off half a liter on his own would indicate that wasn't the first time he'd been down _that_ particular rabbit hole. “I wouldn't—why would I want you dead? Dust is useless.”  
  
For half a second, sans actually dared to be reassured. That was, of course, right up until Pap followed it with, “I'd _keep_ you.”  
  
He touched so gently at the ridge of sans's kneecap, the line of his elbow, rubbed a soothing thumb along the joints. He smiled softly. He looked _pleased._ “I'd just....take 'em off. Right here. N' here. Can't go anywhere if you can't _walk_.”  
  
It took sans a long, blank minute to get it. He really, really didn't want to, if he's being honest, because what parent wanted to even think that their charge was going to grow up into the kind of monster that thought _cutting off his limbs_ was an acceptable response to abandonment?  
  
When it finally clicked, when he finally wrapped his sluggish, stupid brain around _take 'em off,_ icy realization sunk into his stomach like a fucking hunk of concrete hurled into a still pond, shock rippling through his entire body. He trembled, hard enough to make his bones rattle against each other.  
  
“you'd...what,” he rasped faintly, praying he'd heard wrong.  
  
“Take 'em,” Papyrus repeated, like he thought sans might be slow. This time, he accompanied it with a little chopping motion and a _click_ of his conjured tongue, for clarity.  
  
sans was abruptly in real, actual danger of vomiting. “pap, you can't...you can't _keep_ people.”  
  
“Sure,” Papyrus agreed easily. “But you're not _people_. You're mine.”  
  
He didn't even say it meanly.  
  
That's what really worried sans, that right there, because that was....pretty fucked up. That was out of left goddamn field and Pap was totally calm about it, sockets half-closed in lazy contentment. He half-unwrapped himself from sans's frozen grip and slumped back against his headboard instead. From beneath the ragged hem of his black t-shirt, sans could see the soft, familiar glow of his brother's soul, its light honey-warm and pulsing steady. He wasn't upset in the _least_.  
  
_Shit_.  
  
  
  
*  
  
When Papyrus finally makes his move, sans is.........well, 'drunk' might be putting it lightly.  
  
He's at that wavering stage of inebriation where he's got a handful of events, none of which _quite_ slot together in sequential order, and only flashbulb impressions of anything in between.  
  
There had been Grillby's, and there had been beers he'd put on his tab and shots he didn't—because Doggo kept challenging him to round after round of darts despite losing spectacularly every time, the blind bastard. He'd been a persistent little shit about it, too, even after one of his more errant darts had struck uncomfortably close to Lesser Dog's eye, and he'd received a heavy boot to the stomach in recompense.  
  
(sans doesn't _remember_ laughing himself sick at that, precisely, but he definitely would've.)  
  
There had also been this rabbit monster in an obscenely tight skirt perched on his lap for a good chunk of those hazy memories and he _thinks_ he might have fucked her in the dingy single-stall, but he can't be totally sure.  
  
None of his hookups ever leave echoes of the night before on his bones like his brother does, anyways. How is he supposed to remember otherwise? He vaguely thinks he _might_ recall getting her number— although if she's smart, she gave him a fake. She (probably) slept with sans, though, so.  
  
All available evidence points to the contrary.  
  
He kind of recalls being shoved out the door far past closing time by an irate Grillby, but how he managed to make it home from there is anyone's guess, really. He's completely certain he couldn't manage to stand upright at that point. He couldn't do it now if he tried.  
  
Not that he really _wants_ to.  
  
He knows this much: He's collapsed into the couch, his body unfamiliarly lax and far too heavy. He's got an empty glass clutched in his claws. His shirt is....somewhere. His sweatpants are around his ankles and he's not even supposed to be _sitting_ on the couch, but Papyrus had pointed and snarled and he'd dropped like a puppet with its goddamn strings cut.  
  
He'd been prepared for a lecture, the usual _and where were you this time, who were you with, where do you even get the gold to pay for this_ but Papyrus hadn't said so much as a word. He'd poured sans another drink, actually, which... that in and of itself should have been cause for alarm. Pap didn't drink very much himself, but even sans's bleary eyelights noted the ease with which he mixed the whiskey and lemonade, like he'd been practicing. Possibly, he had.  
  
Besides, Papyrus only ever drank clear liquor, as far as sans knew, but he made one for himself, too, which. That....didn't add up. That didn't quite make sense.  
  
sans wrinkled his nasal cavity at the taste, but he slugged the drink back obediently anyways. Pap's got a sweet tooth he wouldn't admit to under interrogation so it was a cloying, gritty feeling in his mouth as a result, though Pap seemed happy enough with the awful concoction. The disgusting sweetness cut the sharp taste of cheap whiskey, anyways. He still wasn't entirely sure he'd call the experience an improvement.  
  
He was still trying to figure out how Papyrus had managed to make the lemonade simultaneously too sweet and sour, staring down the bottom of his empty glass when Papyrus kicked his legs apart and dropped to his knees on the carpet between them.  
  
“ _hey_ ,” sans said, more out of reflex than anything else, but Papyrus just threw back the rest of his drink, dropped the empty glass to the floor, tugged resolutely at the drawstring of sans's sweatpants and—well.  
  
Papyrus sucks cock like he's trashed. That's probably because he learned it from someone who _was_ , for the most part, every single time they did this so sans doesn't really have anyone to blame but himself. They don't ever talk about it, but sans is fairly certain he's the first—maybe the only— monster Papyrus has been with, so he likely just...doesn't have much context otherwise. Doesn't have any real prior experience to draw from. And shit, it's not like _sans_ is complaining.  
  
It's hot and wet and messy, no real, concentrated attempt at getting him off, but it's also surprisingly light on the biting. sans watches, fascinated, as his own fingers curl around the sharp arc of his brother's cheekbone, as the soft gleam of Papyrus's tongue drags a slow trail down the heavy line of his cock from root to tip, pressed flat there for a moment before those wicked teeth _finally_ part to let him in.  
  
sans moans before he can stop himself, though he does shove a knuckle into his mouth to bite down onto, hard.  
  
Papyrus doesn't do this often. Not properly. It's a power thing, maybe, some kind of stupid dominance play, like he thinks there's a chance at all sans might be confused about their places.  
  
He hates being on his knees, he complains often and loudly. He hates being lower than sans. He hates being _vulnerable._ sans, however, privately thinks it's probably just some kind of instinctive macho bristling at the sweet, wrecked little sound his brother makes in the back of his throat when sans shoves his hips up _hard_ into that slick heat. Thinks that it might have something to do with the way Papyrus's eyelights flicker with furious arousal when he chokes, when sans's hand moves around to the back of his skull to hold him in place more securely anyways, like...well, like he _likes_ being throatfucked by his barely-coherent guard dog.  
  
Papyrus pulls off with a damp little _pop_ and slants his narrowed eyelights up to sans's. He sneers, and spits on the carpet, barely missing sans's right foot. “I can _taste_ her on you,” he hisses.  
  
sans's stomach twists at that but his brother doesn't elaborate on the point. His claws on sans's femurs clench tight for a moment. They bite in hard and sans's stupid brain reads that _all_ wrong, doesn't it, shudders a low groan from between his teeth instead of the pained yelp he's shooting for.  
  
Papyrus snickers.  
  
“You disgust me,” he murmurs, but he doesn't sound all that terribly upset about it. He drags the back of a hand over his mouth. “Do you even know her name?”  
  
sans shrugs one shoulder, not trusting his shaky voice with Papyrus knelt between his legs like that, eyelights fixed on him, hungry. sans is straddling this fine line between his brother's molten temper and....something black and unfamiliar in the crooked way Pap smiles up at him. He doesn't know what's on the other side of that line. He _does_ know he has exactly zero interest in finding out.  
  
“You're far better with girls than I'd have thought,” Papyrus observes. “Considering you can barely make it through your own name without tripping over yourself.”  
  
He says it lightly, coolly, like he doesn't mean to be cruel, but that horrible thing in the cradle of sans's pelvis hooks and pulls anyways. He shivers, not unpleasantly. “'S better when I'm drunk,” he slurs, and it's true, somehow, despite the way his words all kind of lean into each other. “plus. you don't really need to _talk_ that much, y'know?”  
  
He doesn't really have a real explanation for what he does, but Papyrus isn't wrong—sans is considerably more successful in that department than his brother is, at least. Papyrus doesn't mention it often, despite the obvious way it grates at him, but when he does, when he _demands_ to know how sans manages it when he can barely make eye contact...sans doesn't know how to explain it at all.  
  
He doesn't have any idea how to tell his little brother that has no wit, no charisma, no number of heavy-handed come-ons or terrible jokes that would at all compare to his simple ability to recognize that hollow, gnawing despair in another monster's eyes that means they're willing to let anyone crawl into their bed. Any _thing._ And, well, it ain't like he can afford to be picky.  
  
He kind of prefers the ones that look right through him, anyways.  
  
“Did she blow you?”  
  
sans opens his mouth on instinct, stammers out something that's the aborted beginnings of a protest in his own defense. She might have, for all he knows, but he's quick enough to put together that Papyrus doesn't want to hear anything close to an affirmative when he's still knelt in front of sans like that.  
  
Before he can manage more than a word, though, Papyrus has two claws in his mouth _,_ pushed hard into the hinge of his jaw, pinning it open.  
  
Papyrus smiles sweetly. He hooks his thumb and foreclaw deep into the meat of sans's tongue, just behind the single, thin gold barbell shoved through the center and _pulls_. sans yelps, startled, jerking back before he really thinks it through and of course, Papyrus's claws catch on the jewelry. Of course.  
  
_Ow_.  
  
Papyrus's eyelights glow a pleased kind of rose at the sound, warm and wholly unfamiliar as he smirks down at sans. He tugs almost thoughtfully at the appendage, just enough to hurt, just enough to wrench a little cry of protest from the back of sans's throat.  
  
“Did you return the favor?” He asks it almost gently, though his claws bite into sans's tongue _hard_ , like they plan on meeting in the middle. “Did you get on your knees for her, too, sans? I know how much you like being on the floor.”  
  
sans can't answer that for a number of reasons, not the least of which is that he _can't fucking remember_. Pap knows it, if the amused slant to his eye sockets is any indication, just like he knows there isn't an answer in the universe he could give that would at all change the outcome here. Papyrus is nothing if not committed.  
  
sans just makes a muffled kind of sound in response, this wordless little protest that sounds far too much like a sob for his own liking. His brother's claws sink minutely deeper in response, just enough for the copper tang of his own blood to flood his palate.  
  
“Do you even have any idea?” Papyrus hisses and sans shakes his head as shallowly as he can manage. “You could take on the whole canine unit and never have any clue in the morning, couldn't you, you _useless goddamn addict_.”  
  
If sans had full command of his mouth still, he'd point out how ridiculous that statement is. Greater Dog's size alone, he doesn't think he'd be able to walk, after, but...Papyrus doesn't actually want to hear an explanation here, anyways, does he? This is the part where he wants to hear himself talk, where, when he's in one of these overflowing, violent moods he'll at least do sans the favor of laying out in excruciating detail the exact nature of his transgressions.  
  
(That, at least, is a damn sight better than the days he's silent and brutal and impossible to please. Those days, one wrong step, and Pap strikes to breaks bone.  
  
But he always looks so much calmer, after.)  
  
“You're an embarrassment,” he's saying when sans tunes back in, so. Business as usual, then. Nothing new there. “Do you even think about how it reflects on me? On your _family_?”  
  
sans blinks once, twice, and...laughs in his brother's face.  
  
He doesn't mean to, really, and he certainly doesn't do it because he thinks it's what Papyrus wants to hear, but he laughs and he laughs and he laughs and his tongue is dripping a steady stream all down the back of his throat now, warm and thick and _choking_ _him_ and still, he keeps right on laughing.  
  
His family! Oh, that's—that's a fucking _riot,_ isn't it, just the thought that any of Papyrus's precious honor is pinned on him at all, that whatever mess he makes of himself in the local dive bar on a nightly basis is in _any_ way related to his brother's obsessive work ethic. That he, what, he has some kind of legacy that he's contributing to here? That he's more than an outdated piece of hardware Papyus has kept around long past its expiration date, because there's a stupid, bewildering sentimentality under his prickly exterior?  
  
That his brother is desperate enough for companionship to call the dog _family_.  
  
“Stop it,” Papyrus growls, flustered, his cheekbones reddening as sans just peters off into hysterical little giggles instead. “I said _stop it_ , sans, stop—stop _laughing_ at me!”  
  
And that, oh, that can't be a good thing, the way his brother's voice creaks on that last word, even if he does finally release his grip on sans's tongue.  
  
sans can feel himself abruptly seized around his borrowed soul, can feel the warm weight of Papyrus's blue magic even before he hears the familiar little _ting_.  
  
Papyrus doesn't bother trying anything more than brute force, just drags him from the couch and slams him to the ground _hard_ , pinning him flat on his back. sans sputters, chokes on his mouthful of blood and saliva. he can feel the awful mixture dripping down his chin where his teeth don't notch together right.  
  
Generally, Papyrus doesn't have the control over his blue magic that sans does. He can't manipulate gravity, really, not in any deliberate way, and he can only really manage a single direction. For obvious reasons, he often chooses straight down.  
  
Papyrus does, however, have a _lot_ more strength than sans. He finds that he can't move a fucking thing, save for the erratic twitching of the very tip of his tail.  
  
Papyrus just sort of watches him for a few long moments, arms folded lazily over his broad chest, one brow raised.  
  
“I need you to summon your tongue again,” he says, softly. “And if you dispel it before I expressly tell you to, I'm gonna _take your fucking legs off._ You hear me, runt?”  
  
See, sans knows how this is gonna go.  
  
This isn't his first time at this particular rodeo—though it had been practice, last time, it had been Pap's pink little tongue poking out between his teeth and his steady hands and a stern _don't move, I don't wanna fuck this up._  
  
Last time, Papyrus had been a kid. He had just been practicing on any available fleshy surface, because Undyne had insisted there was no way she could pierce her fins properly on her own. Naturally, that meant that Papyrus had to learn. Last time, he'd been gentle and quick and let sans suck on a cupful of ice chips after, to numb the throbbing pain.  
  
Last time, Papyrus hadn't been making a point. Papyrus had asked _permission_.  
  
“copy that,” sans croaks. “yep, read you loud and clear.” He sticks the thing out obediently, already bracing himself even before Papyrus settles over him, one knee on either side of sans's ribcage.  
  
He sits back and sans grunts as his brother's considerable weight drops fully onto his chest. He doesn't protest, of course, doesn't do anything but stare blankly up into dilated pink eyelights as Papyrus takes hold of his tongue again and pulls it almost taut.  
  
“Who knows where _that's_ been,” Papyrus muses to himself, deadpan. “You don't like vodka, do you?”  
  
He doesn't, but it's not a question he's expected to answer. It's not like disliking alcohol keeps him away from it, anyways—just means it's the last thing he'll go after, when he gets really desperate. sans squints. Papyrus might be making a joke. It's really hard to tell.  
  
Papyrus reaches for a half-filled bottle on the scarred coffee table with his free hand. It's sealed, bizarrely, with a cork, which he pulls out with his teeth. “You're gonna want to breathe through your nose,” is all the warning he's given before Papyrus tips the liquor into his open mouth and—  
  
—he is choking, he is dying, he is _drowning_ in it, there's the sharp bite of alcohol flooded in whatever passes for his sinuses, all down his throat, spilling between his teeth and all over his shirt, fuck, he'd just _washed_ that but it probably doesn't matter actually because Papyrus is going to kill him here anyways and there's a beautiful, awful kind of irony to all of this, he's literally drowning in his fucking drink and it's _hilarious—_  
  
—and then Papyrus pulls the bottle back. He lets go of sans's jaw enough that he can suck down a huge lungful of air. His throat burns like he's been drinking battery acid. Papyrus still has his tongue held tight between his claws.  
  
“I _told_ you to breathe through your nose, dumbass,” Papyrus growls, setting the bottle aside. “You'll thank me when you don't get an infection.”  
  
Which...he knew where this was going, okay. He gets the whole _theme_ of it. He's not an idiot. But it's one thing to know what his brother is planning and to actually see it, an impossibly thick needle clenched between Papyrus's claws, its chamfered tip glinting in the flickering light of the tv.  
  
(Onscreen, Mettaton appears to be eviscerating a lizard monster dressed in black lingerie. She doesn't look upset about it at all.  
  
He kisses her and hands her a thick, pearly coil of her own intestine. She blushes.  
  
The crowd goes _wild_.)  
  
It doesn't actually hurt when Papyrus puts the needle through his tongue, is the thing.  
  
It's more the noise that gets him, really, metal slammed into wet meat, and the faint _popping_ sensation of the needle pushing out the other side. A dull kind of heat follows as his animal brain kicks into overdrive, alerts him that there's a foreign fucking object shoved through a part of his body, but it certainly doesn't hurt any worse than, say, a broken femur. Feels more like a bad bruise, a deep, pulsing thing right into the very core of him.  
  
“You like it?” Papyrus purrs. With two fingers, delicately, he twists the needle counterclockwise.  
  
sans whimpers as the metal drags against the wound and yeah, okay, _there_ it is, that sets his tongue neatly alight with a bright blaze of pain. He knows better than to move, but he screws his eye sockets shut, clamps down determinedly on the unwilling tears prickling at the corners. “What's the matter?” Papyrus soothes and pets the back of his skull, long, gentle strokes that send a confused shiver down his spine, even as the fingers of the other hand tweak at the makeshift piercing. “It looks good on you.” He pauses. “I think it's a little off-center, though.”  
  
And Papyrus can't stand for _anything_ out of place, so sans just keeps his eyes firmly shut for the next attempt.  
  
And the next.  
  
He gets it right that third time, apparently, though by that point sans's entire skull is filled with a grayish haze of pain, a faint buzzing where his brother's voice would be. He only dimly registers Papyrus fumbling at his tongue with another barbell, his claws slipping on the tiny ball as he attempts to fasten the thing.  
  
He doesn't wipe away the blood when he's finished. sans swallows and he swallows and he swallows and the damn thing keeps right on bleeding anyways. He can feel a thick rope of it sliding down his jaw, can feel the coppery taste pulse out with every beat of his nonexistent heart.  
  
It doesn't make sense. It's his own construct, his own shaky magic, false nerve responses feeding directly into his brain.  
  
He could dispel the tongue and it would stop. This single, awful hurt he can actually fix. Instead, he lets his brother tip another long shot of vodka into his mouth.  
  
sans screams when it hits the new piercings, this low, ragged animal moan as it burns its way into his reddened flesh. He chokes down the acrid taste of blood and vodka best he can with his stomach threatening rebellion. He _whimpers_.  
  
Papyrus pets him again.  
  
“Good,” he says. “You gotta keep it clean. No whiskey for a few weeks.”  
  
Which sounds like good advice, doesn't it, seems reasonable—they've used vodka in their medical kit for years, though the stuff currently soaking into the collar of sans's t-shirt comes from Pap's expensive personal stash—because whiskey is mostly, sugar, right. It seems like a standard kind of procedure, to care for a new piercing.  
  
He nods, dazedly, and wriggles his tongue a little. He's rewarded with a white-hot pain for his efforts.  
  
Except. Except Papyrus is still straddling him. Except Papyrus is kind of wriggling his way up sans's body, and his claws are reaching for the buckle of his stupid studded belt. Except he's unzipping his ratty jeans and he's not wearing anything underneath.  
  
This...does not seem like proper aftercare.  
  
“It's okay if you cry,” Papyrus says gently.  
  
sans doesn't, of course. He's not totally sure he can, come to think of it, not just on _command_ like that, but Papyrus looks amused anyways by the way he shakes his head frantically as unyielding fingers pry his quivering jaw open.  
  
He smiles, this slow, creeping, beatific thing when sans's sockets go wide and blank as Papyrus pushes his cock into that slack mouth, shoves right up against the bright puncture marks.  
  
The pseudo-skin is hotter there, swollen tight around the holes he'd punched in his brother's tongue and Papyrus just kind of....ruts at him lazily for a while like that, making these soft sounds of encouragement that border precariously on praises when sans finally manages to relax himself long enough to take Papyrus into the back of his throat.  
  
He doesn't choke, obviously. It's just... it's easier that way to blank out, to let himself go lax, to detach himself neatly from the throbbing agony in his mouth. He manages to stare at nothing but empty air as Papyrus grabs his jaw in both hands, groans and comes sticky-wet down his abused throat. He doesn't see the look on his brother's face when he does it.  
  
It doesn't feel so weird that way, somehow.  
  
It's only when Papyrus rolls off of him and flops heavy to the carpet that he even realizes there's a tall, dark shape in the doorway behind Papyrus.  
  
sans closes his eyes. Not much guessing room for who that is, but still, he flinches when Gaster snaps, sounding appalled, “ _Really_ , boys? In the living room?”  
  
“Go fuck yourself,” Papyrus says, largely to the ceiling, instead of his father. sans isn't sure Papyrus even realizes he's got one hand curled around sans's jaw still, much less that his grip tightens, just a fraction, when Gaster only sighs, long-suffering, and vanishes from the doorway.  
  
“Stay away from Undyne,” Papyrus says flatly, once he's gone. “I'm not gonna tell you twice. I don't care whatever bar trash you wanna fuck behind Grillby's, but don't you _ever_ touch her again. Got it?”  
  
sans nods, mutely.  
  
It's probably nothing. It's probably just wishful thinking on his part, but he _thinks_ the razor lines of Papyrus's shoulders might ease at that, just a little. Thinks there's might be something like relief in the heavy weight of his skull tipping onto sans's shoulder.  
  
“ _Good_ ,” Papyrus breathes into the sweaty curve of his neck.  
  
He's quiet for a long, long time after.

**Author's Note:**

> uhhhhh let's see. the body parts mentioned when undyne is getting her hair braided are the names for an angler fish's little head lamp and stalk thing, cause i headcanon her like [this](http://vstheworld.tumblr.com/post/137164876438/fishwife)
> 
> undyne's mom and pap's mom were old war buddies. i....think that's it? 
> 
>  
> 
> warnings: business as usual in this 'verse, sans is bad at consent, undyne is a precious, furious little angel who has just realized she is Very Gay


End file.
